Strapping machine



Dec. 12, 1939. T. w. J. wlLLcox 2,183,286

STRAPPING MACHINE l Filed May 1B, 1958' 2 Sheets-Sheet 1 IIIA-gingen mil' Dec. l2, i939. T w, J. wlLLcOx 2,183,286

STRAPPING MACHINE Filed Mgy 18. 1938 z'sneets-sheet 2 Patented Dec. 12, 1939 UNITED STATES PATENT OFFiQE STRAPPIN G MACHINE Brentford, Englandl Application May 18, 1938, Serial No. 208,673

In Great Britain July 14, 1937 14 Claims.

This invention relates to strapping machines and is more specially concerned with the gripping and tensioning of the strapping material used therein.

It is an object of the invention to provide, for gripping one end of a length of strapping material irl a strapping machine, a device which is movable from a position in which the insertion of the strapping material is facilitated to a position in which it holds the gripped strapping material in operative relation to the joint-forming mechanism of the machine.

Another object is to provide a gripping device which is mounted upon the base of the machine for pivotal movement about a vertical axis from a position such that the strapping material can be inserted axially from the front of the machine to a position such that the gripped strapping material is properly presented to the jointforming mechanism.

It is a further object to provide a gripping device comprising a pair of gripping members, the mutual approach of which is prevented by a member which is actuated to release them upon strapping material being inserted between the Jaws.

With the above and other objects in view, the invention consists in the improved combinations and arrangements contained in the embodiments lnow to be described in detail, and features of which are set out in the claims which follow.

l In the drawings: u

Fig. 1 is a front view of the machine,

Fig. 2 is a plan view of the machine,

Fig. 3 is an ,elevation oi a detail, partly in section on the line III-III of Fig. 2,

Fig. 4 is a section on the line IV-IV of Fig. 2 and,

Fig. 5 is a section on the line V--V of Fig. 4.

The machine has the usual slotted twisting pinion I and a gripping device 2 for the free end of the wire is situated on one side of the pinion (on the left as seen in Fig. 1) and a tensioning,

device on the other side: a wire severing device, `including a cutter 3, is provided between the pinion and the tensioning device.

The gripping device 2 for holding the free end of the wire comprises a pivoted gripping member, in the form of an eccentrically mounted wheel d f with a serrated edge, which is spring-pressed to cause it to tend to pivot to bring its gripping surface into contact with an anvil 5, a portion of the upper surface of which slopes downwardly away from the pinion towards a vertical stop it ,i (see Fig.3).

(Cl. 14o-93) The anvil is formed integrally with a member 6 which is arranged for limited pivotal movement about a vertical axis and is spring-pressed4 to pivot away from the pinion. 'Ihe gripping member 4 is mounted on the member E, so that, when 5 the member 6 is in the normal position shown in Fig. 1 and in full lines in Fig. 2, the wire which will afterwards run from the gripper to the pinion may be pushed endwise into position from the front of the machine at an angle of about l0 45 to the pinion axis.

Fig. 3 illustrates the construction of the pivoted member 6 and associated parts. As shown, the member 6 is mounted for pivotal movement about the axis of a bolt l and is urged l5 toward its normal position by a spring 8 which is yhoused in an annular recess 9 in thel member t and has its opposite ends anchored in holes in the member 6 and the base of the machine respectively.

The spring provided to press the gripper member 4 toward gripping position is shown at l@ with one end secured to the member 6 and its other end secured to a portion il projecting rearwardly from a plate I2 which is secured to 25 the front face of the member 4.

The plate I2 has also an upwardly extending portion I3, which acts as a trigger for the release of the Wire at the end of the tying operation, and a lower forward projection I4 between which and 30 the anvil 5 the outer bight of wire may pass on its way from the adjacent edge of the package to its second insertion in the slot of the twisting pinion.

The tensioning device comprises l a pair` of gripping devices, that remote from the twisting pinion being slidable in the longitudinal direction of the Wire to apply tension thereto, and the other stationary and capable of holding the wire to maintain the tension during the return stroke of the moving device.

The moving gripping device comprises a member l5 mounted for movement in a slot it, the axis of which is inclined slightly upwardly with relation to the axis of the twisting pinion, a handle Il being provided whereby the member I5 may be moved against the action of a spring I8 which tends to return it toward the stationary device. f

The movable member I5 has formed within it 5@ upper and lower internal surfaces which converge toward the end of the member adjacent to the stationary device. Upper and lower gripping jaws I9 and 20 respectively having correspondingly inclined upper and lower surfaces respec- J tively are arranged to slide in contact with these surfaces and each has a spring urging it toward the stationary device so that the jaws tend to be pushed into mutual contact by the inclined surfaces. The adjacent surfaces of the jaws are serrated.

The jaws are slightly bevelled so that a wire may be easily inserted between them when introduced sideways through a slot 2| provided in the front of the member I 5. In order to facilitate the introduction of the wire between the jaws, a fixed cam or projection 22 is provided to engage the jaws when the member I is in its normal position, that is its position nearest the stationary device, as constrained by the spring I8; the function of the cam or projection is to cause the jaws to slide relatively to the inclined internal surfaces of the member I5, against the action of their respective springs, to such an extent that they can be forced apart at least to the extent of the smallest dimension of the wire to be inserted. Preferably, the edges of the jaws adjacent to the stationary device are bevelled so that the cam or projection engages between them and forces them apart.

The stationary device comprises a member 23 similar to the member I5 of the movable device and having upper and lower internal surfaces 24 and 25 respectively converging toward the twister pinion; upper and lcwer jaws 26 and 21, having serrated surfaces between which the wire may be inserted sideways by way of a slot 28 in the front of the member, are arranged to slide against the converging surfaces as in the movable device and are similarly spring-pressed, by springs 29 and 3U, so as to tend to approach each other.

In this case the ends of the jaws adjacent to the twisting pinion are inclined in plan as shown in Fig. 5. The springs 29 and 3U normally hold the jaws in contact with the inclined face or taper of a plunger 3| which is mounted in a hole 32 in the back wall of the space in which the jaws are mounted and is spring-pressed so as normally to project toward the front of the machine into the paths of the jaws. The arrangement is such that the jaws are normally held by the plunger in such positions relatively to the surfaces 24 and 25 that their gripping surfaces may be easily forced apart to a distance greater than the minimum dimension of the wire.

In the use of the machine, the operator pushes the end of a wire drawn from a coil between the anvil 5 and the left hand gripping member 4, the latter pivoting as required against the action of the spring ID, until the end of the wire contacts the stop 46.

The end of the wire is now held fast by the gripping device, any tendency of the wire to move in the direction of withdrawal causing the gripping member to pivot to grip it more tightly, and the operator places the adjacent portion of the wire in the slot of the twisting pinion and passes the wire through a holding slot 47 and round the package or the like to be tied: when he pulls the wire tight the member carrying the gripping member and anvil is caused to pivot about its vertical axis, to take up the position shown in dotted lines in Fig. 2, so that the Wire gripped therein comes into line with the slot in the pinion. The arrangement is such that, when the gripping device is in this position the outer, that is the forward, edge of the gripping member is situated substantially in the vertical plane passing through the axis of the pinion with the result that a properly gripped wire is correctly positioned in the slot of the twisting pinion.

The gripped portion of the wire, more-over, takes up a position appropriate to define the end of the knot, that is to say, it comes to lie as far to the left of the pinion as the holding slot 41, which defines the other end of the knot, lies to the right. The pivotal arrangement of the gripper thus not only facilitates the insertion of the wire but also makes it possible, without waste of wire, to insert a wire axially into a gripper which defines one end of the knot.

The wire is then passed under the members I5 and 23 of the tensioning device, round the package and between the anvil 5 and projection I4 of the plate I2, to be inserted a second time into the slot of the twisting pinion and into the slot 47.

'I'he portion of the wire between the slot 4T and the coil is then pressed sideways through the slots 28 and 2| of the members 23 and I5, the pressure on the plunger 3| pushing it out of the paths of the jaws 26 and 2l, which are thus a1- lowed to slide along the inclined surfaces, under the action of their springs, to grip the wire tightly and prevent any backward movement of the wire during the return movement of the movable gripper of the tensioning device.

Various other arrangements operable by the wire could be used to keep the jaws 26 and 21 open and prevent them from gripping the wire until the latter has been fully inserted between them.

A wire-retaining hook 33 is provided between the movable and stationary grippers of the tensioning device and has an inclined face upon which the wire operates, when pushed sideways to enter the slots 2| and 28, to cause it to pivot, against the action of a spring indicated in dotted lines at 34 in Fig. 2, to allow the wire to pass behind its hook portion.

At the completion of the tying operation, when the wire has been severed adjacent to the twisted knot, the end of the wire coming from the coil can be easily removed from the machine, without any necessity to raise the wire-retaining hook, by pulling it toward the coil, when it will be able to slide freely between the jaws of the movable and stationary gripping devices. The end portion of the wire will be found to be free of any serious damage by the tensioning device and ready for insertion in the pivoting gripper device at the beginning of the next tying operation.

The end of the knot on the left hand side of the twisting pinion is defined by the anvil 5, in conjunction with the gripping member 4 and the plate I2, whilst a holding slot 41 is provided for defining the end of the knot on the right of the pinion.

The advantage of the pivoted gripping device is especially apparent when oval or flat strapping material is used: such material can be bent about its major axis only with difficulty so that it is not possible to resort to the expedients ordinarily employed for facilitating the axial insertion of a round wire, such as arranging the gripping device with the opening between its gripping surfaces permanently inclined at an acute angle to the front of the machine, the wire being bent after insertion to bring it into operative relation with the joint-making mechanism.

It is to be understood that a specic form of apparatus has been described above by way of example and that various modifications may be made without departing from the invention.

.I claim: I -1.A.gripping device for forming part of a strapping machine of the type comprising joint forming mechanism for joining overlapping portions of a length. of strapping material, said gripping device serving to hold one end of' a length of strapping material and being mounted for movement from a normal position to provide for insertion of the end of the strapping material endwise in a direction inclined to that of thevstrapping material when in normal position in the strapping machine, to an operative position to place the strapping material in Aline with the joint forming mechanism of the machine, the change in position ofthe gripping device from the normal position for the insertion of the material to the operative position of the material in line with the joint forming mechanism being secured by the action of drawing the material round and pushing it in position in the joint `forming mechanism in a direction transverse to its longitudinal axis.

2. A gripping device for holding the end of a length of strapping material in a strapping machine, said gripping device being conveniently movable from a forwardly facingy normal position to provide for the ready insertion of the strapping material endwise from the front of the machine to a final operative position in which the longitudinal axis of the material runs straight to the joint forming mechanism of the strapping machine, the change in position of the gripping device from a normal to an operative position by moving the strapping material beyond the gripping device toward and pushing it into operative position in the strapping machine.

3. `A construction as dei-ined in claim 1, includl ing a stop for limiting the endwise insertion of the strapping material.

4. A construction as dened in claim 1, wherein the direction of insertion of the strapping material when the gripping device is in normal position is inclined at approximately 45 to the direction of the strapping material when the grip-ping device is. in operative position.

5A. A construction as deined in claim l, wherein means are` provided to influence the gripping device to movement from the operative to the normal position. v

y 6. A strapping machine including a base member, joint-forming mechanism for joining the overlapping portions of a length of strapping material and a gripping device for holding oneend of the strapping material pivotally mounted upon said base member and comprising an anvil member, a gripping member, means for urging said gripping member toward said anvil member, and

a stop member for limiting the axial insertion of strapping material between said anvil member and said gripping member.

7. A strapping machine including a base member, joint-forming mechanism for joining the overlapping portions of a length of strapping material and a gripping device for holding one end 8. In a strapping machine, a device for gripping strapping material comprising a pair of mutually inclined surfaces a pair ofy jaws mounted between said surfaces, spring means urging said jaws'to move along said mutually inclined surfaces in the y direction to cause them to approach each other,

a member mounted for sliding movement in a direction at right angles to the direction inV which said jaws are urged to move by said spring means, a spring tending to urgesaid member into the path of said jaws, said member and said jaws having co-operating inclined surfaces which come into mutual contact when said member is in the path of said jaws.

9. In a strapping machine, a tensioning device for strapping material comprising a, stationary gripping device and a movable gripping device, said movable gripping device comprising a gripping member, a second gripping member, spring means urging said second gripping member to lapproach said rst gripping member and a member operable to prevent said second.

gripping member from approaching said first tionary gripping device, a pair of gripping jaws4 mounted between said surfaces, spring means tending to urge said jaws to move along said inclined surfaces in the direction toward said stationary gripping device, and a member which engages said jaws as said movable gripping device reaches the end of its travel inthe direction toward said stationary gripping device and acts upon them to oppose the action of said spring means.

11. In a strapping machine, a tensioning device as claimed in'claim 10, said member which engages said jaws being a cam .member which spreads said jaws apart.

12. A strapping machine comprising jointforming mechanism for joining the overlapping portions ofa length of strapping material and a tensioning device for tensioning the strapping material, said tensioning device comprising a stationary gripping device and a movable gripping device, said stationary gripping device comprising a pair of gripping jaws and a member arranged to keep said jaws apart until released by the insertion of strapping material between said jaws from the front of the machine in a direction transverse to its longitudinal axis, said movable gripping device comprising a pair of gripping members and a member arranged to engage saidy 1 gripping members and spread them apart as said movable gripping device reaches the end of its travel in the direction toward said stationary gripping device.

13. A strapping machineA comprising jointforming mechanism for joining overlapping portions of alength of strapping material, a gripping device situated on one side of said joint-forming mechanism and mounted for pivotal movement about a vertical axis, and a gripping device mounted on the other side of said joint-forming mechanism .and comprising a pair of jaws, means tending to urge said jaws together and means for hindering the mutual approachof said jaws until tripped by the insertion of strapping material between said jaws from the front of the ma- 10 material from between said gripping members to prevent their mutual approach under the action of said spring means, and said movable gripping device comprising a pair of gripping members, spring means for causing the mutual approach of said gripping members and means for preventing mutual approach of said gripping members un der the action of said spring means when said movable gripping device is in the normal position to which it returns at the end of the tensioning operation.

THOMAS W. J. WILLCOX. 

